import SDI signal and video board to Eevee from the real world camera
Yes but extensive coding are required.

You will need to provide an API for the SDI signal and the capture card with Blender(maybe socket). And inside the Blender, you will need to deal with video sequence in real-time, this is not an easy job in Blender for now, you might need an custom shader to fetch data from socket and display it directly without Blender bpy module since it is slow for massive data like video.

And also a lot of function and operator in Blender are not optimized for video processing, which EEVEE only provide view-port real-time. Manipulating data while being real-time rendered require specified condition, like pre-build asset, baking environment light and so on. We are still making it possible for nowadays hardware. Blender with EEVEE is not designed to deal with this kind of task. I would personally recommend other software, eg. Unity.